The two projects described in the 76/77 annual report, Z01-AM-29016-02-LCP, have been continued and extended: (1) light scattering has been supplemented by birefringence measurements to study the melting and repolymerization measurements of gels of hemoglobin S. Light scattering and turbidity have been used to systematically investigate initial progress curves for the polymerization reaction. (2) Studies on CO hemoglobin have been extended by inducing the reaction by photodissociation of carbon monoxide. An argon-ion laser is used with the existing microspectrophotometer, permitting observation of the polymerization reaction at rates over 1,000 times faster than we were previously able to measure. Collaborative contributions have been made to other projects involving the mechanism of hemoglobin S polymerization in pure deoxy solution and in mixtures with other hemoglobins.